Sporulation, germination, and enzymic control mechanisms were studied in Bacillus subtilis as model of differentiation. Sporulation requires manganese because phosphoglycerate mutase (purified and shown to be an enzyme of 75,000 MW) specifically requires manganese for activity. A mutant deficient in fructose diphosphatase was able to grow on malate and to sporulate normally, suggesting the existence of a bypass of gluconeogenesis. Sporulation, which cannot take place in the presence of excess glucose and ammonia, could be induced by intermediate concentrations of specific inhibitors of nucleotide synthesis, such as decoyinine, hadacidine and 6-azauracil. Two enzymes dehydrogenate glucose: inositol dehydrogenase and glucose dehydrogenase which is made only inside forespores. The outgrowth of spores can be accelerated by the addition of a peptide mixture. BIBLIOGRAPHIC REFERENCES: Cooney, P.H., and Freese, E.: Commitment to sporulation in B. megaterium and uptake of specific compounds. J. Gen. Microbiol., 95: 381-390, 1976. Cooney, P.H., Whiteman, P., and Freese, E.: Media dependence of commitment in Bacillus subtilis. J. Bacteriol., 129(2): 901-907, 1977.